Flat display devices are widely classified into a light-emitting type display device and a light-receiving type display device. Examples of the light-emitting type display device include an organic light-emitting display device (OLED), a plasma display panel (PDP), a flat cathode ray tube (FCRT), a vacuum fluorescent display panel (VFD), a light-emitting diode (LED) panel, and the like. Examples of the light-receiving type display device include a liquid crystal display (LCD) panel and the like.